Sealing cup for electrostatic precipitators

ABSTRACT

Sealing cup centrally traversed by a conductor for use as a safeguard against the formation of overpressure and subpressure in electrical precipitation apparatus. The sealing cup substantially comprises a trough partially filled with a sealing liquid and having a plurality of annular chambers and a bellshaped member arranged to dip thereinto having a plurality of bell-shaped cylinders arranged so as to concentrically project into each of the annular chambers in the trough.

Unitedv States Patent 72] Inventors Werner lbach Knapsack near Cologne; Leopold Slawiczek, l-lermulheim near Cologne, both of Germany [21] Appl. No. 852,663 [22] Filed Aug. 25,1969 [45] Patented Dec. 14, 1971 [73] Assignee Knapsack Aktiengesellschalt Knapsack bei Cologne, Germany [32] Priority Sept. 26, 1968. [33] Germany [31] P17826394) [54] SEALING CUP FOR ELECTROSTATIC PRECIPITATORS 10 Claims, 4 Drawing Figs.

[52] U.S.Cl 174/11811,

55/104, 55/146,174/15 BH,174/3l.5 [51] Int. Cl. .1. B03c 3/34, HOlb 17/26 [50] Field of Search 188/94,

100,100R,100S;174/8,9R,9 F, 11 R, 11 BH, 14BH, 15 BH, 16 BH,17.06,18, 31 R, 31.5; 55/101, 104, 120, 146; 204/302 1 56] Relerences Cited UNITED STATES PATENTS 1,429,914 9/1922 Lewers 174/31.5 X

Rathbun OTHER REFERENCES English Mechanic and World Science, 1889, Vol. 49, published by E. J. Kibblewhite, London, p. 319- 320, Title of Article, A New Balance," made by Eurie, copy of pages 319- 320 in 188/94.

Primary Examiner-Laramie E. Askin Altorney--C,onnolly and Hutz ABSTRACT: Sealing cup centrally traversed by a conductor for use as a safeguard against the formation of overpressure and subpressure in electrical precipitation apparatus. The

sealing cup substantially comprises a trough partially filled with a sealing liquid and having a plurality of annular chammu/0 z 1' Vi!- $144010: role SEALING CUP FOR ELECTROSTATIC PRECIPITATORS The present invention relates to a sealing cup which is somewhat similar in shape to a pneumatic dashpot which is centrally traversed by an electric conductor, used as a safeguard against the formation of overpressure or subpressure in electric filters or electrical precipitation apparatus and substantially comprises a trough partially filled with a sealing liquid and a bell-shaped member arranged to dip thereinto. An electrical precipitation apparatus is an apparatus which substantially comprises a metallic casing which is grounded and fitted with a gridlike metal frame to which is applied the positive pole of a high voltage DC source. The apparatus is used to effect the electrostatic precipitation of dust particles from gas.

A conventional sealing cup of the type described above is designed as an oil cup which is simultaneously used as an insulator and a safeguard against the formation of overpressure. At the level of the filter head, the power supply tube or tubular conductor running from the outside to the filter spray system is arranged to be concentrically surrounded by a duct which runs from the filter heart to the oil cup. The trough is made slightly higher than the duct and substantially half its volume is filled with an insulating oil. The conductor has a metallic bellshaped member secured thereto which is arranged approximately level with the upper rim of the trough and to project into it as deeply as dictated by the pressure prevailing,

The oil cup described above with the conductor running from the head of the electrical, precipitation apparatus to its spray system is not fully satisfactory. Upon the occurrence of overpressure inside the filter, the oil therein is expelled and gaseous and vaporous matter may then escape from the filter inside into the atmosphere through the space left between the bell-shaped member and the trough. In those cases, for example, in which the gas escaping from the oil cup is carbon monoxide and phosphorus in vapor form coming from inside the filter-these are evolved, for example, during phosphorous production-heavy fire outbreaks are very liable to occur, which may be accompanied by damages not only to neighboring facilities but also to the operating personnel standing close by.

A further deficiency resides in the fact that gas escaping from an oil cup-this means lack of homogeneity for the electric fieldmay effect (a) electrical flashing over or disruptive discharges firstly between the duct and the bell-shaped member and secondly between the trough and the bell-shaped member, and (b) fire outbreaks inside the oil cup. in this case, it is also possible for atmospheric air to penetrate into the filter and effect explosion,

The object of the present invention is to provide a sealing cup of the type described above which, however, is free from the deficiencies reported and designed to permit safe operation with respect to fire outbreaks and disruptive discharges. To this effect, it is substantially necessary in accordance with the present invention to provide a sealing cup wherein the trough is formed with a plurality of, preferably with two, annular chambers and wherein the bell-shaped member is formed with a plurality of, preferably with two, bell-shaped cylinders arranged so as to concentrically project into each of the annular chambers in the trough. The sealing cup so designed fully satisfies the requirements set forth above. More particularly it enables the escape of gas normally accompanied by fire outbreaks and explosions occasioned by atmospheric air penetrating to the filter inside to be efiectively obviated.

The invention also provides for the bell-shaped member to be made of electrically insulating material and for the trough to be made of metal, for example iron. The fact that the bellshaped member consists of electrically insulating material enables the sealing cup to be filled with water, replacing the insulating oil. In accordance with the present invention, the inner annular chamber of the trough is filled with a quantity of water corresponding to the pressure prevailing, whereas the outer annular chamber is kept free from liquid. The water present in the sealing cup definitely avoids fire outbreaks.

In accordance with a further feature of the present invention each of the inner and outer annular chambers has a liquid-level indicator placed therein, which enables the quantity of water still present in the inner annular chamber after a given operation period of the sealing cup and the quantity of water expelled from the inner annular chamber into the outer annular chamber under the superpressure prevailing inside the filter, to be monitored from the outside.

The invention still further provides for a sealing gas to be introduced slightly above the electrical precipitation apparatus into the duct concentrically surrounding the power supply line or conductor, placed between the electric filter and the sealing cup. CO-gases and phosphorus vapors coming from the electrical precipitation apparatus are thereby prevented from penetrating into the sealing cup and from effecting short-circuits or disruptive discharges or flashing over therein.

in accordance with a still further important feature of the present invention the upper end of the bell-shaped member is arranged to be connected to an annular chamber receiving a sealing gas travelling through an annular slit formed at the filter side, between the annular chamber and the conductor, This is an additional safeguard against the possible penetration into the sealing cup of CO-gases and phosphorus vapors in those cases in which they should actually remove the barrier of sealing gas introduced just slightly above the electric filter.

The invention further provides for a precipitation chamber having a coiled baffle element therein to be connected by means of a duct to the upper end of the outer bell-shaped cylinder or to the outside wall of the trough. This enables CO- gases and phosphorus vapors which escape from the sealing cup and which possibly include fractions of sealing liquid, to be passed through the duct to the precipitation chamber in which they are precipitated, using the baffle element therein, and returned to the sealing cup.

In order to make it possible for the sealing liquid fractions retained particularly in the precipitation chamber to be returned to the inner annular chamber of the trough, it is advantageous for this latter chamber to be formed near its upper end with an outwardly directed conical extension. The invention also provides for the outside wall of the trough to be connected to a bellows so as to avoid inside soiling of the trough.

Four exemplary representations of the apparatus of the present invention are shown diagrammatically in the accompanying drawings, wherein:

FIG. 1 is a representation of the sealing cup having a sealing liquid supply pipe disposed just above the electrical precipitation apparatus;

FIG. 2 is a representation of the sealing cup of FIG. 1, formed with an additional annular chamber connected to the upper end of the bell-shaped member;

FIG. 3 is a representation of the sealing cup shown in FIG. 2, formed with a branch line connecting it to a precipitation chamber, and

FIG. 4 is a representation of the sealing cup shown in FIG. 3 with a slightly modified branch line connection to the precipitation chamber.

The sealing cup shown diagrammatically in the accompanying drawings is used as a safeguard against the formation of overpressure or subpressure in electrical precipitation apparatus, particularly filters of the type used in the production of phosphorus. As can be seen. the sealing cup mounted on housing I of the electric filter (not shown in the drawing) is centrally traversed by a conductor 2 and secured to the filter head by means of flange 3. The sealing cup internally bounded by duct 4 substantially consists of trough 5 partially filled with a sealing liquid and bell-shaped member 6 which is arranged to dip thereinto. The sealing cup is formed with two annular chambers, namely outer annular chamber 7 and inner annular chamber 8. This latter chamber 8 is filled with a quantity of water corresponding to the pressure prevailing. Needless to say any other noncombustible liquid can be used to replace the water. The outer annular chamber 7 is kept free from liquid at least during the startup or first use of the sealing cup.

Bell-shaped cylinders 9 and 10, which form part of the bellshaped member 6, are arranged so as to project into each of the two annular chambers 7 and 8 of trough 5, concentrically with respect thereto. in other words, bell-shaped cylinder 9 is arranged to project into outer annular chamber 7 and bellshaped cylinder 10 is arranged to project into inner annular chamber 8. The bell-shaped member is made up of electrically insulating material. This is done in order to obviate electrical flashing over or disruptive discharges from trough 5 to bell shaped member 6, and inversely. The trough can be made up of metal. for example iron, as in the past.

Each of the inner annular chamber 8 and outer annular chamber 7 is fonned with a liquid-level indicator 11 or [2, which enables the quantity of water expelled by the overpressure prevailing inside the filter from the inner annular chamber 8 into the outer annular chamber 7 to be monitored in time. More particularly, liquid-level indicator 11 is placed in inner annular chamber 8 and liquid-level indicator 12 is placed in outer annular chamber 7.

FIG. 1 shows the introduction of a sealing gas, which preferably is hot CO-gas, through gas supply line 21 and apertures 22 into power duct 4.

As shown in FIG. 2, the upper end of bell-shaped member 6 is connected to an annular chamber 23 having a sealing gas inlet 13. At the filter side between annular chamber 23 and conductor 2 there is formed an annular slit 24, through which the sealing gas is introduced into the sealing cup.

As shown in FIG. 3, the upper end of the outer bell-shaped cylinder 9 is further arranged to be connected by means of conduit 18 to a precipitation chamber 15 having a coiled baffle element 17 therein. As shown in FIG. 4, it is also possible for conduit 18 to be connected to the upper end of outer wall of trough 5. This enables conduit 18 to be made rigid as it does not participate in the movements of bell-shaped cup member 6. Baffle element 17 is intended to arrest the further passage of liquid droplets carried along into the precipitation chamber 15 once gas escapes from the sealing cup.

It is also advantageous for the inside wall 19 of trough 5 to be formed at its upper end with an outwardly directed, conical extension (14). The outside wall 20 of trough 5 is connected to bellows 16 to avoid the deposition of dirt in it.

The invention is in no way limited to the exemplary representations shown in the accompanying drawing and admits of various modifications without departing from its scope. More particularly, it is possible for the sealing cup shown in the drawings to be replaced with a device having more than the two annular chambers 7 and 8 and accordingly more than the two bell-shaped cylinders 9 and 10 shown therein.

We claim:

1. A sealing cup for use as a safeguard against overpressure and subpressure in an electrical precipitation apparatus comprising a trough, a bell-shaped member and a conductor, said trough being centrally transversed by a duct and having a plurality of annular chambers, said annular chambers being subdivided into inner and outer annular chambers, said bellshaped member having a plurality of bell-shaped cylinders concentrically projecting into each of said annular chambers in said trough, said conductor passing centrally through said duct and bell-shaped member, said bell-shaped member being constructed of electrically insulating material, and said trough being constructed of metal.

2. A sealing cup as claimed in claim I, wherein said trough has two annular chambers and said bell-shaped member has two bell-shaped cylinders.

3. A sealing cup as claimed in claim I, wherein said trough is iron.

4. A sealing cup as claimed in claim I, wherein the outside wall of the trough is connected to a precipitation chamber having a baffle element placed therein.

5. A sealing cup as claimed in claim 1, wherein the inner annular chamber of the trough is filled with a quantity of water corresponding to the pressure prevailing and the outer annular chamber is kept free from liquid.

6. A sealing cup as claimed in claim 1, whereln each of the inner and outer annular chambers has a liquid-level indicator placed therein.

7. A sealing cup as claimed in claim 1, wherein said duct concentrically surrounds the conductor and said duct is connected to a gas supply line delivering sealing gas to it slightly above the electrical precipitation apparatus, between the electrical precipitation apparatus and the sealing cup.

8. A sealing cup as claimed in claim 1, wherein the upper end of the bell-shaped member is connected to an annular chamber receiving a sealing gas travelling through an annular aperture formed at the filter side, between the said annular chamber and the conductor, to the sealing cup.

9. A sealing cup as claimed in claim 1, wherein the upper end of the outer bell-shaped cylinder is connected to a precipitation chamber having a baffle element placed therein.

10. A sealing cup as claimed in claim 1, wherein the inside wall of the trough is formed at its upper end with an outwardly directed, conical extension. 

1. A sealing cup for use as a safeguard against overpressure and subpressure in an electrical precipitation apparatus comprising a trough, a bell-shaped member and a conductor, said trough being centrally transversed by a duct and having a plurality of annular chambers, said annular chambers being subdivided into inner and outer annular chambers, said bell-shaped member having a plurality of bell-shaped cylinders concentrically projecting into each of said annular chambers in said trough, said conductor passing centrally through said duct and bell-shaped member, said bell-shaped member being constructed of electrically insulating material, and said trough being constructed of metal.
 2. A sealing cup as claimed in claim 1, wherein said trough has two annular chambers and said bell-shaped member has two bell-shaped cylinders.
 3. A sealing cup as claimed in claim 1, wherein said trough is iron.
 4. A sealing cup as claimed in claim 1, wherein the outside wall of the trough is connected to a precipitation chamber having a baffle element placed therein.
 5. A sealing cup as claimed in claim 1, wherein the inner annular chamber of the trough is filled with a quantity of water corresponding to the pressure prevailing and the outer annular chamber is kept free from liquid.
 6. A sealing cup as claimed in claim 1, wherein each of the inner and outer annular chambers has a liquid-level indicator placed therein.
 7. A sealing cup as claimed in claim 1, wherein said duct concentrically surrounds the conductor and said duct is connected to a gas supply line delivering sealing gas to it slightly above the electrical precipitation apparatus, between the electrical precipitation apparatus and the sealing cup.
 8. A sealing cup as claimed in claim 1, wherein the upper end of the bell-shaped member is connected to an annular chamber receiving a sealing gas travelling through an annular aperture formed at the filter side, between the said annular chamber and the conductor, to the sealing cup.
 9. A sealing cup as claimed in claim 1, wherein the upper end of the outer bell-shaped cylinder is connected to a precipitation chamber having a baffle element placed therein.
 10. A sealing cup as claimed in claim 1, wherein the inside wall of the trough is formed at its upper end with an outwardly directed, conical extension. 